Thermal relay



THERMAL RELAY Filed June 24, 1956 FIG.1.

ATTORNEY Patented Apr. 4, 1939 PATENT OFFICE THERMAL RELAY Oscar S. Field, Rochester, N. Y., assignor to. General Railway Signal Company, Rochester,

Application June 24, 1936, Serial No. 87,068

5 Claims.

More specifically, it is proposed in accordance 15 with this invention to provide means whereby the position of a fixed front contact can be adjusted, whereby to vary the requisite amount of travel of a movable contact, and thereby vary the time of operation of the relay. 7 20 Further objects, purposes and characteristic features will appear as the description progresses, reference being made to the accompanying drawing showing, ,solely by wayv of example, and in no manner in a limiting sense, one form which the invention can assume. Inthe drawing:-

Fig. 1 is an elevational view with parts shown in section.

Fig. 2 is a sectional view on line 2-2 of Fig. 1, viewed in the direction 'of the arrows. an The relay of this invention is of the same general type as shown in Patent 1,902,793.' patented March 21, 1933, to J. E. Willing, and in general involves a compensated bi-metallic thermal 'element carrying movable contacts which operate between a fi ired back contact and a fixed front contact, and; measure atime interval during its travel from ;the fixed back contact to the fixed front contact and back again tothe fixed back contact.

40 Referring now to the drawing, the. device includes a housing I, having a top plate 2, in which is a groove 3;; for receiving the upper ends of rigid brackets 4 and .5, respectively carrying a fixed back contact 6, and a'fixed front contact 7.

45 The brackets 4 and 5 are clamped in position by means of binding posts 8 and "I. It can be seen from the sectioned portion of the post 10, that its threaded stem is passed up through the top plate to bring a fixed head II is position to 5 clamp bracket against, the top plate as a tightening nut I2 is screwed down against the top face of the top plate. The other bracket l is attached to the top plate in thesame manner as just described.

55 The movable contact member I2 is compensated for ambient temperature changes, but this need not be described herein since it constitutes no part of the present invention. This movable contact number I2 is carried by the top plate, by binding post 9 in the manner described above, 5 and has a heating element l3 which, when energized, causes the movable contact member l2'to move to the left and make contact with fixed contact l, and when ale-energized to return to its shown position, where it makes contact with fixed 10 contact 6.

Referring now more particularly to the binding post I0, it isseen that this post is hollow, and recelves a stem 14, having a head l5 thereon whichv bears against the head ll of the post, to thereby l5 limit the upward movement of stem l4. On the outer end of stem i4 is a thumbnut l6, pinned thereto, and this thumb nut i6 is furnished with a seal l'l, whereby to attach it to a plate l8, keyed to the post [0, whereby to prevent turning of the thumb nut it when the seal is in place, there being a plurality of apertures in the plate l8 for variously receiving the seal.

Carried by the inner end IQ of stem H, which inner end is threaded, is a rectangular box-like traveler 20, received on this threaded'end, and restrained from rotation therewith by the bracket 5, which is received between the-two arms 2| of member 20. Also carried by the two arms 2| is a roller member 22, which bears against the spring carrying member 23 of fixed contact 1, this member 23 being formed, as shown in Fig. 1, to be inclined inwardly toward the lower end of threaded stem l9.

With this arrangement of parts, it can be seen that rotation of thumb nut l6, causes the threaded stem l9 to rotate, to thereby cause traveler 20 to move along the stem so that roller 22 bears against, and results in movement of, fixed contact 'I either to the right or the left, according as the 40 traveler moves downwardly or upwardly.

Should there be no safeguard against improper adjustment of thecontacts, it would be possible to move fixed contact 1 so as to make contact with movable contactmember l2, with the relay de-energized} and thereby defeat the time measuringfunction of the relay. To avoid any such misuse of the adjusting means, a stop nut 24 is positioned on' threaded stem l9, and locked in position, as by a set screw 25, in such a position as to limit the traveler 20' to a travel just insufllclent to cause fixed contact 1 to make contact with movable contact member l2 when the relay is deenergized.

With the above structure it is clear that, should the relay constant, even though there be variations in the voltage applied to the heating .winding II, this can be accomplished by adjusting the position of the'ilxed contact I with respect to the movable contact member l2,

Furthermore, in various situations, it is desirable to cause the relay to measure various different elapsed time periods and here again and adjusting means of this invention premits ready and accurate adjustment of the position of the front fixed contact, to thereby vary the time, as desired, and within the limitation of the structine involved. Y a

It can be seen that, with the threaded stem 19- causing the traveler 20 to move, very minute and accurate movements of the traveler can be obtained, and the traveler can be held accurately in adjusted position without any danger of disturbing the desired position thereof, while fixing this adjustment by means of seal M. This threaded traveler member is thus much more desirable for effecting adjustments than other mechanical means which would lend themselves less readily to accurate minute adjustments and definite fixing of the adjustment after it is obtained.

The above rather specific description of one form of the present invention is given solely by way of illustration, and is not intended, in any manner whatsoever, in a limiting sense. Obviously the invention can assume various physical forms, and is susceptible of numerous modifications, and all such forms and modifications are intended to be included in this application, as come within the scope of the appended claims.

Having described my invention, I now claim:

1. In a thermal relay, in combination, a casing, a top plate on the casing, a movable contact carried by the top plate, a hollow post on the top plate, a rigid support bracket clamped between the post and the plate, a front contact spaced from the movable contact, a stem passing through the hollow post, a thumb nut on the outer end of the stem, a threaded inner end on the stem, a spring arm connecting the front contact to the bracket and spaced from the threaded innerend, a threaded traveller on the inner end ofv the stem, a bifurcation in the traveller receiving the bracket, and cam means on the traveller bearing against the spring arm to vary the position of the front contact 2. In a-thermal relay, in combination, 9, casing, a top plate on the casing, a movable contact carried by the top plate, a hollow post on the top plate, a rigid support bracket clamped between the post and the plate, a front contact spaced from the movable contact, a stern passing through the hollow post, a thumb nut on the outer end of the stem, a threaded inner end on the stern and extending parallel to, and spaced from, the

it be desired to maintain the operating time of a threaded traveller on the inner end of the stem. a bifurcation in the traveller receiving the bracket, cam means on the traveller bearing against the spring arm to vary the position of the front contact upon movement of the traveller, and a stop member fixed to the threaded end of the stem and so positioned as to prevent the traveller from causing the front contact to touch the movable contact.

3. In a thermal relay, in combination, a movable contact, a fixed contact spaced therefrom, a spring arm carrying the fixed contact, a rigid bracket spaced from, and inclinedto, the major part of the spring arm. and carrying the same, a threaded stem spaced from, and substantially parallel to, the bracket, means for turning the stem, a bifurcated nut on the stem, the bracket being received in the bifurcation of the nut for preventing rotation of the nut with the stem, and a roller carried by the nut and bearing against the spring arm, whereby to cause the nut to travel on the stem when the stem is turned and the roller to move the fixed contact.

4. In a thermal relay, in combination, a movable contact, a fixed contact spaced therefrom, a spring arm carrying the fixed contact, a rigid bracket spaced from the major part of the spring arm and carrying the same, a threaded stem spaced from, and substantially parallel to, the bracket, means for turning the stem, a bifurcated nut on the stem, the 'bracket'being received in the bifurcation of the nut and preventing rotation of the nut with the stern, and a roller carried by the nut and bearing against the spring arm, whereby to cause the nut to travel on the stem when the stem is turned and the roller to move the fixed contact, said spring arm being inclined toward the bracket so as to cause.the roller to always bear thereagainst and produce a camming action on the spring arm and fixed contact upon movement of, the nut.

5. In a thermal relay, in combination, a movable contact, a fixed contact spaced therefrom, a spring arm carrying the fixed contact, a rigid bracket spaced from part of the spring arm and carrying the same, a threaded stern spaced from, and substantially parallel to, the bracket, means (or turning the stem, a bifurcated nut on the travel of the nut before the contacts touch each a other.

' OSCAR S. FIELD. 

